Football players are usually the ones who realize the benefit of regular weight training the most, I think, which is only natural with such a physical contact sport. But, a baseball player can hit the ball harder if he works out, building arm and chest strength. Basketball players can jump higher. Soccer players can kick the ball farther and more accurately. Heck, even a bowler could get better control of his game - the bottom line is that a strong, coordinated physique will result in better control and power in every sport.
Make note though: brute strength shouldn't take the front seat in every sport. The priorities should lie in coordination, flexibility (that means stretching, people), and most important of all: Equal development! Tennis players are extreme examples. They practice, sometimes daily, using ONE arm and ONE side of the body to swing the racquet.
After a couple of years, a singles tennis-player will find that one arm is considerably stronger, that one leg is slightly thicker than the other, and possibly a slight discomfort in the back as they walk for any length of time. You'd be a fool to not realize that the working side of your body has grown stronger, and that this imbalance plays a certain role in your back pain.
The cure is simple: Train with weights to equalize your body. This does not mean going crazy with some 1-arm exercises, but more put the focus on training in a way that will put equal demand on both sides of the body. For example, chest presses with dumbbells make sure the stronger pectoral muscle can't pull a little extra weight for the weaker muscle, as it would during a barbell bench press. There are a lot of really good machines that work this way, particularly the Hammer Strength-series. You get the idea.
Avoiding Shortened Muscles
I mentioned stretching. This is essential to make sure there's actual benefit to weight training. What use is extra power to a golfer, if the training has made him inflexible so his swing is compromised? For sports that involve a lot of running, especially football and soccer, I want to point out that there's one muscle you want to be sure to keep flexible - the hip flexor. A shortened hip flexor will pull your spine in an awkward position for every step you take, and send a shockwave of bad news up your entire structure.
Also keep in mind that proper stretching is a thing to take seriously - and might differ considerably from some traditional stretching practiced in different sports. Don't be afraid to approach your coach or trainer about this, if you suspect he's advocating a "traditional" way that might be non-productive or harmful!
A few signs that he or she is not on track:
- 'Bouncing' at the max point - in ANY muscle stretch!
- Leg stretching with locked-out knees.
- Forced stretching that results in pain.
- Not following the contract-release principle.
There are a lot of details involved of course, but if you recognize any of the above signs, it might be worth looking into. It's not about embarrassing the coach - it's about the good of the team. Bring a book for reference when you approach him, and make sure to keep a positive attitude that is not threatening to his authority. Always do this 1-on-1.
No, I'm not going to do a re-run of the first section. Instead, it's a re-run of the typical bodybuilding nagging - don't just train you favorite muscles! For a bodybuilder, chest and biceps are generally much more fun to train than the hamstrings. Hey, you can see the biceps, but who really spends time admiring one's own hamstrings in the bathroom mirror?
While an ice skater wants to keep the legs in shape, he might ignore the upper body. An arm wrestler probably won't put his calves high on the priority list.
Just because you don't necessarily need a particular muscle group in your sport, doesn't mean you can happily ignore it. The body is more complex than one might think - back and abdominal muscles stabilize the body in pretty much every sport. Legs and hips are involved in racquet sports, since you're doing a twisting movement of the whole body. Even a runner uses his arms and shoulders to maintain good balance (try running a dash with your arms crossed and shoulders stationary!).
The bottom line is that you should strive for balance throughout the body at all times. The reason might not be obvious to you now, but chances are that you'll be grateful somewhere down the road. And for Pete's sake, ignore the nutty advice about "sport-specific" training in the "soft-core" health magazines, advocating that you should only train the muscles you use in a specific sport!